We have studied dopa release and conversion of dopa to dopamine in Dahl salt-resistant (DR) and Dahl salt-sensitive (DS) rats on either low or high salt diet. We found that both strains, DR and DS rate increase drastically their urinary dopa and dopamine excretion in response to high salt diet. The increase in urinary dopa and dopamine was associated with only a mild increase in plasma dopa clearance and spillover. Thus, it seems that dopa and dopamine are synthesized locally in the kidney in response to high salt diet.